For farmers who are serious about producing a nutrition-packed crop that will sustain the herd for optimum production, the year starts with crop planning and seed selection. After planting, it’s mostly a waiting game until harvest.
When kernels reach about 80 percent milk, begin sampling the plant for moisture content. Whole plant moisture level between 65 and 70 percent is ideal. When moisture content exceeds 70 percent, silage juices seep from the bunker, which means loss of soluble nutrients and feed value. Conversely, silage that is harvested too dry presents packing challenges, and excess oxygen that can result in undesirable heating and mold development.
Safety is critical during harvest and filling, so take time to review safety measures with the harvest crew. Crews work at a frantic pace, often with less than optimum sleep, but no crop is worth a life or serious injury. Many farmers use custom harvesters, and it’s the responsibility of the farm owner to ensure a safe work environment for all workers. Custom operators who use employees should be able to provide proof of insurance and worker’s compensation. Make sure that employees of a custom operator are adequately trained and mature enough to handle large equipment in a hurried environment.
One of the main harvest hazards is presented by continual backing of tractors over the bunker and the potential for collisions with other tractors or trucks coming from the field. As the bunker is packed, rollover risk is high, especially toward the end of the process. Trucks often drive from field to bunkers at a high speed, and pass each other with little room to spare as they move in and out of farm lanes. There’s potential for entanglement in harvest machinery if equipment is stopped in the field for repairs.
Use wide-front end tractors with low clearance and additional weights to ensure stability. Tractors used to pack bunker silos are often working at a significant slope, so any tractors used for packing should be equipped with ROPS (roll-over protection) and seatbelts, and operators should be instructed to use seatbelts. The large dump trucks that are used to bring the crop from the field become less stable as the bed is raised, so drivers should always back up the slope and dump at the lowest possible angle.
Everyone who is operating equipment should be aware of every other person and piece of equipment throughout harvest, filling, packing and covering. Those who are not directly involved in the operation, especially children, should remain clear of the area.
Rapid filling, packing and covering the bunker is the key to uniform moisture and ultimately, feed quality. Prior to harvest, inspect bunker sidewalls for cracks and make appropriate repairs. Any ruts or cracks in the silo floor or approach area should be repaired so that truck and tractor operators can safely dump and pack. Make sure that all equipment is in good working condition and that ample personnel are available to run equipment in both the field and at the bunker.
Check the cut length, which should be 3/8 inch for unprocessed silage and 3/4 inch for processed silage. Proper cut length optimizes packing and minimizes excess oxygen. A kernel processor increases starch availability, but it’s important to ensure that kernels are actually processed and not just nicked. Large kernels are more likely to be fully processed, but if kernels are being nicked rather than broken, check roller clearance and make appropriate adjustments.
Bunkers should be filled from back to front in a progressive wedge to create a 3:1 slope; or a rise of one foot for every three feet of horizontal run. Begin filling the bunker by spreading a thin layer (six inches or less) and drive over that layer several times. Once the first truck is unloaded at the bunker, fill should be rapid and continual. Plan to drive over each layer multiple times with at least one heavy tractor to ensure a solid pack. The time spent packing directly influences fermentation and potential feed loss at feed-out. Toward the end of filling, shape the top of the bunker so that it sheds water.
The bunker should be filled only as high as the retaining walls. Overfilled bunkers cannot be properly sealed and are potentially dangerous to unload. Bunkers should be covered immediately following the final load. Some farmers who have long bunkers begin covering as soon as the rear of the bunker is filled and packed.
Plastic used to cover bunkers should be six to eight mil thick; preferably eight for easier handling and tear resistance. Newer covering systems employ two layers, which should be placed according to manufacturer’s guidelines. Plastic covering should be tight to the surface of the silage and sealed at the edges. Create channels several feet in from the sidewalls to prevent rainwater runoff from seeping between the bunker walls and the silage. Place weights over the plastic covering, and don’t skimp on weights. Weights can be whole or split tires, or nylon bags filled with gravel or sand. The plastic at the edges of the bunker can be sealed with sandbags, soil or ag lime. Take care not to puncture the plastic cover as weights are being placed.
Uniform weight across the bunker helps minimize surface spoilage. During the first several days following covering, watch for areas of flapping plastic that can potentially expose silage to air. Place additional weights as necessary. Inspect the cover regularly, looking for small punctures that can become big tears. Use tape designed for silage cover repair to seal holes.